CONSUMERS ENERGY CO

Incident Narrative

DEBRIS DAMAGED RUBBER REGULATOR BOOTS OF WORKER AND MONITOR REGULATORS AT MILLETT & GUINEA REGULATOR STATION (STATION #428), WEST OF I-69 ON MILLETT HIGHWAY IN DELTA TOWNSHIP, MICHIGAN. THE RESULTING DOUBLE REGULATOR FAILURE RESULTED IN AN OVERPRESSURE OF THE 60 PSIG MAOP DOWNSTREAM SYSTEM. PRESSURE RECORDING CHARTS AT MILLETT & GUINEA REGULATOR STATION RECORDED A MAXIMUM DOWNSTREAM PRESSURE OF 139 PSIG, AN EXCEEDANCE OF 131% OF MAOP. RELIEF VALVES AT TWO SEPARATE REGULATOR STATIONS - SEVERAL MILES AWAY AND BACKFEEDING THE 60 PSIG MAOP SYSTEM - BEGAN BLOWING AS A RESULT OF THE OVERPRESSURE EVENT. ALL TOLD, APPROXIMATELY 3.19 MMCF NATURAL GAS VENTED FROM BOTH VENTS COMBINED. THESE REGULATOR STATIONS ARE: - CREYTS ROAD & M-43, LANSING (STATION #46) + RELIEF VALVE SET PRESSURE = 63 PSIG + MAX PRESSURE RECORDED = 63 PSIG + DURATION OF VENTING = 130 MINUTES - CREYTS ROAD & M-78, LANSING (STATION #47) + RELIEF VALVE SET PRESSURE = 60 PSIG + MAX PRESSURE RECORDED = 94 PSIG + DURATION OF VENTING = 117 MINUTES POLICE AND FIRE DEPARTMENT WAS ON SITE AT THE INTERSECTIONS OF CREYTS & SAGINAW (M-43) AND CREYTS & LANSING (M-78), AND INTERSECTIONS WERE BLOCKED TO TRAFFIC. MEDIA WAS ALSO ON SITE REPORTING. LANSING MALL (5330 W. SAGINAW HIGHWAY, LANSING) AND ST. GERARD CATHOLIC SCHOOL (4433 W. WILLOW, LANSING) WERE EVACUATED AS A RESULT OF THE VENTING INCIDENT. APPROXIMATELY 120 MILES OF GAS DISTRIBUTION MAIN (60 PSIG MAOP) AS WELL AS 7,010 GAS SERVICES (60 PSIG MAOP) IN DELTA TOWNSHIP WERE OVERPRESSURED. LEAK SURVEY AND SUPPLEMENTAL LEAK INVESTIGATION (INCLUDING BAR TESTING) WAS PERFORMED ON THESE FACILITIES BETWEEN JANUARY 29 AND FEBRUARY 7. APPROXIMATELY 42 LEAKS WERE FOUND AND REPAIRED DURING THIS LEAK SURVEY, AND AN ADDITIONAL 92 LEAKS WERE CLASSIFIED FOR FUTURE REPAIR.